1. Field of the Invention
The present invention relates to a fluid analyzer used in a semiconductor manufacturing process, and more particularly to a fluid analyzer capable of sampling process fluids used in a semiconductor manufacturing process for analyzing the process fluids.
2. Description of the Related Art
Generally, semiconductor devices are manufactured by performing a series of unit processes for forming a film, a pattern, and a metal wiring structure on a semiconductor substrate. While the individual unit processes are carried out, more than 40 kinds of gases with responsive, corrosive, and noxious properties and various process fluids including deionized water are used. Such gases can be directly used in a semiconductor manufacturing process as process gases, or can be used as auxiliary gases for maintaining a process environment. In addition, they can be used as carrier gases for moving the process gases to a process chamber in which a process is carried out. Deionized water is used for cleaning the semiconductor substrate between unit processes.
In view of this, the cleanliness of such gases or deionized water directly influences the yield and productivity of the semiconductor devices. That is, if such gases or deionized water contain too many impurities exceeding a predetermined reference level permitted in the unit processes, process failures can occur. Accordingly, the density of impurities and the number of particles in such gases or deionized water are periodically measured through an analyzing process using a fluid analyzer.
Lines for supplying process fluids into devices carrying out the unit processes are widely divided into a main line and a plurality of sub-lines, which branch from the main line and connect to the devices carrying out the unit processes. Process fluids can also be contaminated while passing through each line. Contamination levels in the main line and sub-lines are often times different from each other.
Therefore, in order to improve the productivity of the semiconductor devices, it is preferable to analyze the process fluids by sampling the process fluids from the sub-lines supplying the process fluids. However, it is an expensive undertaking to install the fluid analyzers on the sub-lines. For this reason, the analyzing process is carried out only with respect to the process fluid sampled at the main line. Accordingly, when a process failure occurs in the form of a contamination of the process fluids, much time is required to find a contamination source, thereby lowering the productivity of the semiconductor devices. In order to solve the above problem, studies for analyzing process fluids sampled from a plurality of lines with using a common fluid analyzer have been actively developed.
For example, Japanese Laid-Open Patent Publication No. 6-094733 to Shimada, et al. discloses a switching method for measuring impurities in a plurality of pipes using one fluid analyzer. According to the Shimada's disclosure, a plurality of gas pipes are respectively installed on the fluid analyzer and impurities contained in gases of the plural gas pipes are measured by switching the fluid analyzer with respect to the plurality of gas pipes. Japanese Laid-Open Patent Publication Nos. 9-318609 to Inomata, et al. and 9-196828 to Inomata disclose a gas analyzer having a gas switching device and a gas adjusting section for allowing plural gases to be selectively supplied into the gas analyzer. U.S. Pat. No. 5,841,022 to Hase discloses a gas analyzer and a gas analysis method. According to the Hase disclosure, the contamination of a clean environment is controlled by collecting samples from a plurality of measurement points while switching between these points.